SOURCE OF DATA

The Oxford Regional Health Authority

The Department of Medical Genetics, located in the Churchill Hospital, Oxford, provides a service for the four counties (population 2-52 million) forming the administrative area of the Oxford Regional Health Authority under the National Health Service (Fig. 1). Out-patient clinics provide genetic consultant services in all the NHS general hospitals which together cover the Region, to which general practitioners and consultants in other specialties refer cases. Kindred or family members living outside the Oxford Region may be served by other regional departments, according to where they reside, which, for genetic investigations, will require exchange of information between consultants of different Regions. It is sometimes convenient to agree that one Region should deal with families divided between two or more Regions. Not all Regional Genetic Departments have the resources in staff and experience to maintain a DNA laboratory capable of carrying out presymptomatic linkage analyses in Huntington's chorea and patients will then be referred to the most conveniently situated department of a neighbouring Region. The Oxford Regional Department of Medical Genetics had assembled resources and gained considerable expertise in linkage analysis for some years before the advent of a presymptomatic linkage test in Huntington's chorea.

Subjects

Our subjects were the affected and unaffected members of families with Huntington's chorea who were interested in the presymptomatic linkage test for the gene for Huntington's chorea and living within Oxford Regional Health Authority. In 1985-6 a letter was sent to all families who had previously been referred to and seen by the Medical Genetics Department of the Churchill Hospital, Oxford, for Huntington's chorea, offering an interview to explain the test. To this number was added new referrals for Huntington's chorea from 1985 to 1990.

Families of subjects referred to the Department of Medical Genetics were interviewed either in their homes or at hospital out-patient departments by a psychiatrist and a community nursing sister attached to the department.